Weird hexagonal diamonds from another planet discovered on Earth

Scientists have detected the presence of a rare “folded diamond” that arrived on Earth from outer space via an asteroid.

The material found is known as lonsdaleite, and like a diamond, it’s made out of carbon. The difference is that its crystal structure is arranged in a hexagonal pattern, so lonsdaleite is sometimes referred to as hexagonal diamond.

Lonsdaleite is of scientific interest because the material could theoretically be even harder than regular diamond, suggesting it could have all sorts of industrial applications. Regular diamond is already used in high-end saw blades, for example.

Diamond and Earth
Left: A stock close-up photo of a diamond. Right: A stock illustration showing a space object like a comet or asteroid approaching Earth. Scientists think the diamond-like material lonsdaleite arrived on Earth from space.
Drew Beynon #DBPic/johan63/Getty

Scientists have known about lonsdaleite for at least half a century, after discovering it in meteorite samples, but the amounts discovered have been tiny with crystals measuring just nanometers in size.

Now researchers say they have found significant amounts of the material hidden inside meteorite samples from northwest Africa, with some crystals about 1,000 times bigger than the ones previously discovered.

“It’s really exciting because there were some people in the field who doubted whether this material even existed,” Alan Salek, a physics Ph.D student at the Royal Melbourne Institute of Technology (RMIT) in Australia who was part of the research team, told the New Scientist.

Based on the team’s analysis, it’s thought that the lonsdaleite was formed in a high-energy cosmic collision that occurred over 4.5 billion years ago—perhaps involving a dwarf planet or a very large asteroid.

The heat and pressure caused by this collision would have compressed folded graphite stored inside the mantle of this cosmic object and produced a mix of fluids and gases that would have then been released, leaving the lonsdaleite behind.

It’s not dissimilar to how diamonds are manufactured on Earth using a process called chemical vapor deposition (CVD)—though the difference is the naturally occurring pressure used to form the lonsdaleite would have been higher.

It wouldn’t be the first time we’ve discovered exotic materials from space. Chinese researchers recently said they had found a new phosphate mineral on the moon by studying lunar dust samples they had brought back to Earth.

Nick Wilson, another member of the team who discovered the lonsdaleite in the African meteorite samples, said the new findings could allow researchers to tweak existing diamond-production processes to manufacture lonsdaleite instead.

“So, nature appears to have given us clues on how to make shaped ultra-hard micro machine parts,” he wrote in an article for The Conversation. “If we can find a way to replicate the process preserved in the meteorites, we can make these machine parts by replacement of pre-shaped graphite with lonsdaleite.”

A study outlining the discovery was published in the journal Proceedings of the National Academy of Sciences (PNAS) on September 12.

A file photo of several diamonds shining against a blurred background. The rare material lonsdaleite, discovered in meteorites, could theoretically be harder than diamond.

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